They are selling it as an appliance, not a computing device. So they try to lock things down as much as possible, so people can't mess their device up by accident. Of course this limits it application as a more general device, but its not selling it as a general device.

I don't think it was limited it marketing appeal in any way though, this is being marketed to the general consumer, they are trying to take the Kindle head on. The number of people who would get excited by easy rooting are just not significant. I mean look at Nokia's n900 phone, you can gain root access just by typing sudo gainroot in a terminal. But I've never seen anyone make a big deal of this feature, people only make a big deal about rooting when your not allowed to, otherwise it gets ignored. Used by people who know what they are doing of course, but it certainly wouldn't get a story on os news.